1. Field of the Invention
The present invention relates to aluminum baseball bats which currently are used at the college and lower levels. Such bats typically include a metal shell formed of aluminum or aluminum alloy or other metals, such bats being used not only in baseball but also in softball at such substantially all levels of non-professional levels of play. As referred to herein, the term "aluminum" is intended to encompass aluminum alloys formulated for the manufacture of bat shells.
Recently, the National Collegiate Athletic Association (NCAA) has indicated that, for player safety reasons, the batted ball exit speed for non-wood bats should equate to or not exceed the highest average exit speed using major league baseball quality, 34 inch solid wood bats. Bats meeting these specifications are expected to result in lower incidences of harm to ball players.
2. Prior Art
U.S. Pat. No. 5,395,108 Souders, et al issued Mar. 7, 1995 for a SIMULATED WOOD COMPOSITE BALL BAT comprises a fiber reinforced composite shell filled with expansible urethane foam to develop compressive stresses therebetween.
U.S. Pat. No. 5,114,144 issued May 19, 1992 to Baum discloses a composite baseball bat made to look like a wood bat by using a central core of foamed plastic (foam density of 5-15 lbs/cu. ft.) or extruded aluminum covered with a layer of resin impregnated fiber knitted or woven cloth and a surface layer of longitudinally extending planks or strips of resin coated wood veneer.
U.S. Pat. No. 5,460,369 issued Oct. 24, 1995 to Baum discloses a composite bat having a wood veneer surface bonded to a composite tubular core.
U.S. Pat. No. 5,533,723 issued Jul. 9, 1996 to Baum discloses a composite bat having a wood veneer surface and intermediate composite layer bonded to a tubular core of composite or aluminum. The core may comprise a resilient urethane foam and a cavity may be left in the core in the hitting area and the cavity may be filled with less dense material. The core may vary in density over the length of the bat, preferably with a higher density section near the barrel end.
U.S. Pat. No. 5,458,330 issued Oct. 17, 1995 to Baum discloses a composite bat having a wood veneer surface and cavitied foam core.